It Just Got Easier to Visit a Vanishing Glacier. Is That a Good Thing?

Claude Folmer was about 40 years old the first time he visited the Mer de Glace, the largest glacier in the French Alps. He remembers enjoying the panoramic view from the observation platform, then taking a short hike down to the ice, where he toured the ice cave that’s carved into the glacier’s surface.Four decades later, on a mild, sunny morning in early February, Mr. Folmer — now 80 and accompanied by his…